Enhanced bioremediation of hydrocarbon-contaminated soil using pilot-scale bioelectrochemical systems

Two column-type bioelectrochemical system (BES) modules were installed into a 50-L pilot scale reactor packed with diesel-contaminated soils to investigate the enhancement of passive biodegradation of petroleum compounds. By using low cost electrodes such as biochar and graphite granule as non-exhaustible solid-state electron acceptors, the results show that 82.1-89.7% of the total petroleum hydrocarbon (TPH) was degraded after 120 days across 1-34 cm radius of influence (ROI) from the modules. This represents a maximum of 241% increase of biodegradation compared to a baseline control reactor. The current production in the BESs correlated with the TPH removal, reaching the maximum output of 70.4 ± 0.2 mA/m(2). The maximum ROI of the BES, deducting influence from the baseline natural attenuation, was estimated to be more than 90 cm beyond the edge of the reactor (34 cm), and exceed 300 cm should a non-degradation baseline be used. The ratio of the projected ROI to the radius of BES (ROB) module was 11-12. The results suggest that this BES can serve as an innovative and sustainable technology for enhanced in situ bioremediation of petroleum hydrocarbons in large field scale, with additional benefits of electricity production and being integrated into existing field infrastructures.